Side branched endoluminal prostheses and methods of delivery thereof

ABSTRACT

An expandable prosthetic device and method of delivery that allows the initial placement of multiple guidewires into selected target sites. The prosthesis includes a main body device. This main body device has a separate side branch guidewire lumen that passes through the main body device and through a side opening in the main body device. As the main body device is advanced, the side opening is self guided (by the side branch guidewire) and self-aligns to the side branch vessel ostium. The main body device is then deployed, leaving the side branch guidewire in place. A side branch device is then advanced along the side branch guidewire through the main body device, through the side wall opening and into the native side branch vessel. The side branch device can then be deployed to engage the main body device and the native side branch vessel.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional application of copending and commonlyowned U.S. Ser. No. 11/739,136 filed Apr. 24, 2007.

FIELD OF THE INVENTION

The present invention relates to endoluminal prostheses and methods ofdelivery thereof. The endoluminal prostheses and method of delivery areparticularly suited for use in bifurcated regions of body lumens.

BACKGROUND OF THE INVENTION

Stents or stent grafts are examples of expandable endoluminal prostheticdevices which are used to maintain, open or dilate stenotic lesions inbody lumens or to cover and repair an aneurysm. Vascular disease mayoccur at a branch or bifurcation in a vessel. Placement and deploymentof these prosthetic devices at bifurcations can often be problematic.One current technique is to initially deploy across an aneurysm, a mainbody prosthetic device having a side wall opening. The side wall openingis aligned with the side branch ostium. A second prosthetic device isthen deployed through the main body prosthetic device side wall openingand into the side branch vessel. Procedural complications are oftenencountered while practicing this technique. These complicationstypically relate to the accurate placement of the main body prostheticdevice and in particular to the precise alignment of the side wallopening to the native side branch vessel. Subsequent placement of theside branch guidewire through the main body prosthetic device, throughthe side wall opening and then into the side branch vessel can also beproblematic. The deployment of the side branch prosthetic device intothe native vessel can present problems relating to the longitudinalplacement of the device.

Alternate procedures for treating bifurcated vessels place theguidewires prior to the device deployments. After the main bodyprosthetic device is deployed, it is advantageous to then remove themain body delivery catheter prior to the delivery of the side branchprosthetic device. Typical delivery systems incorporate guidewires thatare contained or captured within the delivery catheter. The catheterremoval therefore requires careful management of the side branchguidewire to prevent its dislodgement during the removal of the deliverycatheter.

SUMMARY OF THE INVENTION

An aspect of the invention includes an expandable prosthesis comprising:

an expandable main body device having a first open end and a second openend, a wall extending from the first open end to the second open end, alumen extending from the first open end to the second open end, and atleast one side opening in the wall; and

guidewire tube having a first end, a second end and a lumen, theguidewire tube extending from at least the main body device sideopening, through the main body device lumen to a point proximal to thesecond open end, wherein the guidewire tube is removable from the mainbody device while the main body device is in a compressed state.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a prosthetic device according to anaspect of the invention.

FIG. 2 is a perspective view of a catheter assembly having a removableside branch guidewire tube.

FIG. 3 is a flow chart listing the process steps used for thefabrication and delivery of a catheter assembly having a removable sidebranch guidewire tube.

FIG. 4 is a perspective view of an expanded main body device with firsttemporary tube routed through the main body lumen and a second temporarytube routed through a side branch support.

FIGS. 5A and 5B are perspective views of a compressed and constrainedmain body device displaying the routing of two temporary tubes.

FIG. 6A is a perspective view of a distal catheter portion.

FIG. 6B is a perspective view of a main body device compressed andconstrained onto a distal catheter portion.

FIG. 7 is a perspective view of a compressed and constrained main bodydevice with a proximal catheter portion bonded to a distal catheterportion.

FIG. 8 is a schematic diagram showing pre-placed guidewires loadedthrough a compressed device with a removable guidewire tube.

FIG. 9 is a schematic diagram showing a side branch guidewire routedthrough a removable guidewire tube.

FIG. 10 illustrates the removal of a side branch guidewire tube.

FIG. 11 is a schematic diagram showing a compressed main body devicepositioned at a branch vessel target site.

FIG. 12 is a perspective view of an expanded main body device having aside branch opening aligned to a side branch vessel.

FIG. 13 illustrates the initial advancement of a compressed side branchdevice.

FIG. 14 shows a compressed side branch device routed through the mainbody device and into the side branch vessel.

FIG. 15 is a perspective view of a fully deployed main body stent graftand a fully deployed side branch stent graft.

DETAILED DESCRIPTION OF THE INVENTION

An aspect of the invention includes an expandable prosthesis comprising:

an expandable main body device having a first open end and a second openend, a wall extending from the first open end to the second open end, alumen extending from the first open end to the second open end, and atleast one side opening in the wall; and

guidewire tube having a first end, a second end and a lumen, theguidewire tube extending from at least the main body device sideopening, through the main body device lumen to a point proximal to thesecond open end, wherein the guidewire tube is removable from the mainbody device while the main body device is in a compressed state.

A further aspect of the invention provides methods for delivery of anexpandable prosthesis that overcome the drawbacks relating toconventional devices and delivery methods. The present invention allowsfor the initial placement of multiple guidewires into selected targetsites. The guidewire placement is simplified since there are noendoluminal devices complicating the guidewire placement. As a failsafe,the procedure can be aborted if the guidewires cannot be properlyplaced. After proper placement of the guidewires is confirmed, a mainbody prosthetic device can be advanced to the treatment site. This mainbody device has a separate side branch guidewire that passes through themain body device and through the side opening in the main body device.Therefore as the main body device is advanced, the side opening is selfguided (by the side branch guidewire) and self aligns to the side branchvessel ostium. The main body device is then deployed, leaving the sidebranch guidewire in place. The side branch guidewire is released as themain body device is deployed. The delivery catheter can then be readilyremoved without dislodging the placement of the side branch guidewire. Aside branch prosthetic device can then be advanced along the side branchguidewire through the main body device, through the side wall openingand into the native side branch vessel. The side branch device can thenbe deployed to engage the main body device and the native side branchvessel.

In an aspect of the invention a side branch guidewire lumen is formed bya relatively short, removable tube. This tube preserves a lumen duringthe compaction and storage of the main body prosthetic device and can besimply removed after a guidewire is inserted prior to the advancement ofthe device into the body. The short length of the removable guidewiretube permits a single operator to back load and advance the device,similar to a conventional balloon catheter configured for “rapidexchange”.

Further understanding of the invention may be had with reference to thefigures. Shown in FIG. 1 is a compressed prosthetic device according tothe present invention.

The expandable prosthesis comprises:

an expandable main body device 40 having a first open end 1 and a secondopen end 2, a wall extending from the first open end 1 to the secondopen end 2, a lumen 3 extending from the first open end 1 to the secondopen end 2, and at least one side opening 42 in the wall; and guidewiretube 32 having a first end 11, a second end 12 and a lumen 13, theguidewire tube 32 extending from at least the main body device sideopening 42, through the main body device lumen 3 to a point proximal tothe second open end 2, wherein the guidewire tube 32 is removable fromthe main body device 40 while the main body device 40 is in a compressedstate.

The expandable main body device can be either self-expanding or balloonexpandable. Typically, a self-expanding device will include at least oneshape memory material, such as nitinol. The main body device cancomprise a stent or stent graft. Suitable stent materials include, inaddition to nitinol, for example, metallic, polymeric or naturalmaterials and can comprise conventional medical grade materials such asnylon, polyacrylamide, polycarbonate, polyethylene, polyformaldehyde,polymethylmethacrylate, polypropylene, polytetrafluoroethylene,polytrifluorochlorethylene, polyvinylchloride, polyurethane, elastomericorganosilicon polymers; metals such as stainless steels, cobalt-chromiumalloys and nitinol and biologically derived materials such as bovinearteries/veins, pericardium and collagen. Stents can also comprisebioresorbable materials such as poly(amino acids), poly(anhydrides),poly(caprolactones), poly(lactic/glycolic acid) polymers,poly(hydroxybutyrates) and poly(orthoesters).

The main body device can comprise a stent at either the first open end,the second open end, or at both the first open end and the second openend. Moreover, the stent can be a single stent extending from the firstopen end to the second open end. In an aspect of the invention, graftmaterial is used to form the wall and extends from the first open end tothe second open end. Grafts can have various configurations and can befabricated, for example, from tubes, sheets or films formed into tubularshapes, woven or knitted fibers or ribbons or combinations thereof.Graft materials can include conventional medical grade materials such asnylon, polyester, polyethylene, polypropylene, polytetrafluoroethylene,polyurethane and elastomeric organosilicon polymers.

Stents can be used alone or in combination with graft materials. Stentscan be configured on the external or internal surface of a graft or maybe incorporated into the internal wall structure of a graft.

Shown in FIG. 2 is a side view of a catheter assembly 20 having aproximal catheter portion 22, a proximal hub assembly 24 and a distalcatheter portion 26. The distal catheter portion 26 comprises a mainbody stent (or stent graft) portion 28. The main body stent is shown ina compressed state, maintained by a constraining sleeve 30. Also shownis a removable side branch guidewire tube 32.

FIG. 3 is a flow chart depicting the assembly and delivery sequence of acatheter system having a removable guidewire tube. Following are detailsrelating to the steps listed on flowchart FIG. 3:

Step 1) Place Expanded Main-Body Device onto First Temporary Tube.

Shown in FIG. 4 is an expanded main body stent graft 40 having a sidewall opening 42 and an internal side branch support channel 44. A firsttemporary tube 37 can be inserted through the stent graft main bodylumen. A first stiffening mandrel can be positioned within the firsttemporary tube. The stent graft can be fabricated, for example,according to the methods and materials as generally disclosed in U.S.Pat. Nos. 6,042,605; 6,361,637; and 6,520,986 all to Martin et al.Details relating to exemplary fabrication and materials used forinternal side branch support channel 44 can be found in U.S. Pat. No.6,645,242 to Quinn.

Step 2) Place Second Temporary Tube Through Side Branch Support.

Referring to FIG. 4, a second temporary tube 41 can be routed throughthe side wall opening 42 and through the internal side branch supportchannel 44 to the second open end 2 of stent 40.

Step 3) Compress Main Body, Add Constraining Sheath

Referring to FIG. 5A, the main body stent can be compressed and held inthe compressed state by a constraining sheath 30. The sheath can belaced together by a deployment cord 46. The sheath lacing forms agenerally longitudinal seam along the constraining sheath. Theconstraining sheath can be provided with a slit 43 that is orientedperpendicular to the longitudinal seam 46. The slit can subsequentlyprovide an exit point for the second temporary tube 41. Additionally,the second temporary tube 41 could exit through the stitch line. Detailsrelating to constraining sheath materials, sheath methods of manufactureand main body compression techniques can be found in, for example, U.S.Pat. Nos. 6,352,561 to Leopold et al., and 6,551,350 to Thornton et al.

Step 4) Route Distal End of Second Temporary Tube Through Slit inConstraining Sheath.

As shown in FIG. 5B, the second temporary tube 41 can be routed throughthe slit 43. A small spring puller or hook can be inserted through theslit and used to engage the lumen of the second temporary tube. Once thelumen is engaged the second tube can be pulled through the slit as shownin FIG. 5B. After the second temporary tube 41 is routed through theconstraining sheath, a second stiffening mandrel 49 can be insertedthrough the second temporary tube.

Step 5) Remove First Temporary Tube and Replace with Distal CatheterPortion.

Shown in FIG. 6A is distal catheter portion 26 having a distal tip 45and a shaft 47. The distal catheter portion 26 has a continuous lumen 36that is sized to accommodate a guidewire. As shown in FIG. 6B, the firsttemporary tube can be replaced by the distal catheter portion 26. Thefirst temporary tube 37 can be removed by placing the lumen 36 of thecatheter shaft 47 onto the stiffening mandrel. The catheter portion 26can then be used to push the first temporary tube out of the compresseddevice. After the catheter portion is fully inserted, the stiffeningmandrel can be removed.

Step 6) Bond Proximal Catheter Portion to Distal Catheter Portion.

As shown in FIG. 7, a proximal catheter portion 22 is bonded to thedistal catheter portion 26 at bonding point 48. A hub assembly 24 isattached to the proximal catheter portion 22. The hub assembly 24 has amain guidewire lumen extending from distal tip 36, through the hubassembly to the proximal tip 39 of the catheter. Also shown is adeployment cord 46 routed through a deployment cord lumen 38 extendingthrough the hub assembly 24.

The catheter and hub can comprise conventional medical grade materialssuch as nylon, polyacrylamide, polycarbonate, polyethylene,polyformaldehyde, polymethylmethacrylate, polypropylene,polytetrafluoroethylene, polytrifluorochlorethylene, polyvinylchloride,polyurethane, elastomeric organosilicon polymers, Pebax® polyether blockamide, and metals such as stainless steels and nitinol.

The proximal and distal catheter portions can have diameters and lengthssuitable for the delivery of a variety of main body stentconfigurations. Catheter diameters can range from about 1 mm to over 20mm, with a preferred range of about 2 mm to about 15 mm, with a mostpreferred range of about 2 mm to about 6 mm. Catheter lengths can varyfrom about 20 cm to over 100 cm.

The removable guidewire tube can comprise the same materials listedabove for the catheter and hub materials. Moreover, the tube can includea reinforcing braid material, such as metal braid.

Step 7) Replace Second Temporary Tube with Removable Guidewire Tube.

As shown in FIG. 7, the second temporary tube 41 can be replaced by aremovable guidewire tube 32. The second temporary tube can be removed byplacing the removable tube onto the stiffening mandrel 49. The removabletube 32 can then be pushed over the stiffening mandrel 49, driving thetemporary tube out of the compressed device. After the removableguidewire tube 32 is fully inserted, the mandrel can be removed and theremovable guidewire tube trimmed to length.

The guidewire tube can be fabricated from suitable medical gradematerials similar to those used in the catheter materials listed in step6) above. The guidewire tube can have inner diameters ranging from about0.1 mm to about 2 mm, with a preferred range of about 0.2 mm to about1.5 mm, with a most preferred range of about 0.3 mm to about 1 mm.

The guidewire tube can have a wall thickness ranging from about 0.05 mmto about 1 mm, with a preferred range of about 0.06 mm to about 0.5 mm,with a most preferred range of about 0.08 mm to about 0.3 mm.

The guidewire tube can have a length tailored for a particular stent. Ingeneral, the guidewire tube is significantly shorter than the overallcatheter length and can be slightly longer than the main body stent. Forexample a guidewire tube can have a length ranging from about 1 cm toabout 30 cm, with a preferred length ranging from about 2 cm to about 20cm, with a most preferred length ranging from about 4 cm to about 15 cm.

Step 8) Place Guidewires into Target Sites

As shown in FIG. 8, two guidewires can be placed into native vessels.Shown are a main body guidewire 50 placed into a main vessel 52 and aside branch guidewire 54 placed into a side branch vessel 56. Anintroducer sheath (not shown) can be used during the guidewireplacement. A hemostatic valve (not shown) is typically used to controlback-bleeding during the guidewire and subsequent device placement.Typical guidewires (with 0.035″ and 0.014″ diameters) can be used.

Step 9) Backload Guidewire Tube and Main Body Device onto TwoGuidewires.

As further shown in FIG. 9, the catheter assembly 20 can be back loadedonto the two guidewires. The main body guidewire 50 is threaded into thecatheter main guidewire lumen 36, while the side branch guidewire 54 isthreaded into the removable guidewire tube 32.

The guidewires are fully inserted through the catheter main body lumen36 and through the removable guidewire tube 32, as depicted in FIG. 9.Shown is a main body guidewire 50 fully inserted through the cathetermain guidewire lumen 36 and a side branch guidewire 54 fully insertedthrough the removable guidewire tube 32.

Step 10) Remove Guidewire Tube from Compressed Main Body Device

As shown in FIG. 10, the guidewire tube 32 can now be removed from thecatheter assembly by withdrawing the guidewire tube 32 in the directionshown by arrows 58. After removal of the guidewire tube 32, a sheathaperture 60 remains, from which the side branch guidewire 54 exits. Anysuitable material may be used to fabricate the guidewire tube 32.Examples of such materials include, conventional medical grade materialssuch as nylon, polyacrylamide, polycarbonate, polyethylene,polyformaldehyde, polymethylmethacrylate, polypropylene,polytetrafluoroethylene, polytrifluorochlorethylene, polyvinylchloride,polyurethane, elastomeric organosilicon polymers and metals such asstainless steels and nitinol. In an aspect of the invention the materialis sufficiently translucent so that the guidewire can be visualized bythe practitioner as the guidewire is advanced through the guidewire tube32. In a further aspect of the invention the end of the guidewire tube32 that extends out the second end of the main body device is closed, orplugged. Thus, when the guidewire is inserted into the guidewire tube 32and advanced toward the second end of the main body device the guidewirewill contact the closed end of the guidewire tube. Further advancementof the guidewire can cause the guidewire tube 32 to advance beyond thesecond end of the main body device where it can be removed by hand.Moreover, to prevent the guidewire tube from being inserted into anintroducer sheath during a procedure, the proximal end of the tube canbe provided with an enlarged portion (such as a flag, knob, largediameter plug, expanded tube end, etc.) that is incapable of fittinginside the lumen of an introducer sheath.

Step 11) Advance Compressed Device to Target Site

The catheter assembly can now be advanced to the target site. As shownin FIG. 11 the catheter and compressed main body device are advancedalong the two guidewires 50, 54 until the sheath aperture 60 is alignedto the side branch vessel 56.

Step 12) Release Constraining Sheath to Expand Main Body Device

As shown in FIG. 12, the deployment cord 46 is pulled in the directionshown by arrow 62. By pulling on the deployment cord 46 the constrainingsheath is split allowing the main body device 40 to self-expand andengage the main vessel 52. The constraining sheath (not shown) can beleft in-vivo since the sheath will be captured between the main bodystent and the main vessel lumen. The side branch guidewire remainsrouted through the main body side wall opening 42, through the internalside branch support 44 and out through the proximal end of the main bodydevice.

Step 13) Withdraw Catheter from Target Site

The catheter 34 of FIG. 12 can now be removed, leaving the expanded mainbody device 40 and the side branch guidewire 54 in place.

Step 14) Backload Side Branch Device onto Side Branch Guidewire.

A compressed side branch stent graft can then be back loaded onto theside branch guidewire. As shown in FIG. 13, the side branch guidewire 54can be inserted into a side branch guidewire lumen 66. The compressedside branch device 64 can then be advanced in the direction indicated byarrow 68. The compressed side branch device can be a stent or stentgraft and can be constructed similar to the main body device 40,discussed above.

Step 15) Advance Compressed Side Branch Device Through Internal SideBranch Support Channel

As shown in FIG. 14, the compressed side branch device 64 can be fullyadvanced along guidewire 54 so that the compressed device exits the mainbody side wall opening 42 and enters the side branch vessel 56.

Step 16) Release Constraining Sheath to Expand Side Branch Device

Referring to FIG. 14, the side branch constraining sheath can bereleased by pulling on the deployment cord 70 along the directionindicated by arrow 72. As shown in FIG. 15, the release of theconstraining sheath allows the side branch device 76 to self-expand andengage the side branch vessel 56, the main body side wall opening 42 andthe internal side-branch support channel 44. The side branch cathetercan be removed after the side branch device is fully expanded. Theconstraining sheath (not shown) can be left in-vivo since the sheathwill be captured in a fashion similar to that of the previous main bodydevice.

The expandable prosthesis of the invention can be delivered to, forexample, the aortic arch branches (arteries of the head, arms, andhands), lower branches of the aorta (celiac), renals, mesenterics,iliacs, the femoral, and lower extremities (legs, feet).

Example 1

An expandable prosthetic device having a removable guidewire tube can befabricated as follows:

1) A self-expanding, main body stent graft can be provided having anouter diameter of 3.1 cm, a length of 15 cm and a graft wall thicknessof about 0.005″. The graft material can comprise ePTFE and FEP and beformed from an extruded and expanded thin walled tube that issubsequently wrapped with ePTFE film. A nitinol wire having a diameterof about 0.0165″ can be helically wound to form a stent having anundulating, sinusoidal pattern. The formed, heat-treated stent can beplaced onto the base graft. An additional film layer of ePTFE and FEPcan be wrapped onto the stent and base graft to selectively adhere thestent to the graft.

2) The main body stent graft can have an internal side-branch supportchannel formed into the graft wall. Details relating to exemplaryfabrication and materials used for an internal side branch supportchannel can be found in U.S. Pat. No. 6,645,242 to Quinn.

3) A failsafe feature to prevent the inadvertent “non-removal” of theguidewire tube can be incorporated into the guidewire tube. A distalportion of a removable guidewire tube can be formed from an 18 cm lengthof Pebax® 5533 tubing having a 304 stainless steel braid(0.00075″×0.003″) and a polyimide inner lumen lining (from PhelpsDodge). The tube can have an outer diameter of 0.0455″ and an innerdiameter of 0.039″. A proximal section of transparent tubing (Pebax®7233, OD of 0.057″, ID of 0.047″, from Specialized Engineering) can becut to a length of about 4 cm.

A 0.038″ mandrel can be inserted into the first distal tube. Thetransparent proximal tube section can be placed over the mandrel so thatthe transparent tube overlaps the first distal tube by about 1 cm. A 2cm long section of 0.060″ ID FEP shrink tubing can be placed onto theoverlapped tube sections. Using a narrow hot box (set at 420° F.), thetube overlap can be heated until the tubes reflow and bond together. Aspherical bead of UV curable adhesive can be applied to the end of thetransparent tubing and cured to form a plug.

When a side branch guidewire is subsequently loaded into the guidewiretube, the transparent proximal section provides visual feedback that theguidewire has advanced through and fully exited the stent graft. Theadhesive plug effectively blocks further guidewire advancement;therefore the stent device cannot be further advanced without removingthe guidewire tube. This failsafe prevents the inadvertent “non-removal”of the guidewire tube.

4) A temporary polymeric tube (such as a PTFE tube) can be threadedthrough the main body stent, through the internal side branch supportand out through the main body side wall opening as shown, for example,in FIG. 4. This temporary tube can be replaced with the removableguidewire tube after compression of the device. The stent device canthen be compressed using temporary tethers and a tapered pull-throughcompression die. The main body stent can be compressed onto a temporarymandrel having a 0.066″ OD and maintained in the compressed state by aremovable constraining sheath. The temporary tube can be removed and thecompressed device transferred onto a distal catheter portion (as shown,for example, in FIG. 6A, item 26). The distal catheter portion can havea shaft OD of 0.068″.

5) A proximal catheter portion (as shown, for example, in FIG. 7, 22)can be bonded onto the proximal end of the distal catheter portion (asshown, for example, in FIG. 7, 26). A unitary hub assembly (FIG. 7, 24)can be bonded to the proximal end of the proximal catheter portion (asshown in, for example, FIG. 7, 22) to complete assembly. The deploymentcord can be appropriately routed through the proximal catheter and hubassembly.

1. Method for delivering an expandable prosthetic device comprising thesteps of: advancing a main body guidewire into a main vessel; advancinga side branch guidewire into a side branch vessel; providing a catheterassembly comprising a first catheter having opposite proximal and distalcatheter portions and a catheter main guidewire lumen; an expandablemain body device disposed along the distal catheter portion and having afirst open end, a second open end, a wall extending from the first openend to the second open end, a lumen extending from the first open end tothe second open end, at least one side opening in the wall; a guidewiretube having a first end, a second end, and a lumen, the guidewire tubeextending through the expandable main body device lumen between at leastthe at least one expandable main body device side opening and a pointproximal to the second open end; and a constraining sleeve disposedaround and compressing the expandable main body device onto a portion ofthe guidewire tube extending through the expandable main body devicelumen; backloading the catheter main guidewire lumen of the firstcatheter and the lumen of the expandable main body device onto the mainbody guidewire; backloading the guidewire tube onto the side branchguidewire; removing the guidewire tube from the compressed expandablemain body device; advancing the first catheter and the expandable mainbody device into the main vessel and aligning the at least one sideopening with the side branch vessel; expanding the expandable main bodydevice by releasing the constraining sleeve; and removing the firstcatheter.
 2. The method of claim 1, further comprising the steps of:providing a second catheter having a distal end, a proximal end, adistal portion, a proximal portion, a lumen extending from the distalend to the proximal end, and an expandable side branch device loaded onthe distal portion; advancing the second catheter and the expandableside branch device along the side branch guidewire through the expandedexpandable main body device, out the at least one side opening, and atleast partially into the side branch vessel; expanding the expandableside branch device; and removing the second catheter.